The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory captions and links exemplifying features within the Earth system. The community is invited to contribute digital imagery, short captions and relevant links.

Twilight Arch

The above photo was taken during the afterglow of day, last summer, in France. Clear, nearly cloudless skies were a result of the mistral (a strong, dry wind that blows down alpine slopes and into the Rhone River Valley in France). Note the twilight arch with Venus near the apex of the arch. The twilight arch is the band of light that lingers after sunset on clear nights, and it's caused by sunlight scattered by the atmosphere. Even though the Sun has set as viewed by an observer on the ground, it's still shining on the sky above. This sunlit twilight arch grows fainter and redder as twilight progresses.